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I used to record the Philadelphia Orchestra in The Academy of Music for WFLN-FM when I was in undergrad school. Also recorded Opera Company pf Philadelphia and Concerto Soloists of Philadelphia which was a very interesting group focused on obscure and modern classical. And we did lots of location recordings of string quartets and piano recitals, some famous players.

One time EMI hired us to place spot mics around the hall which they intended to mix in for ambience on a Muti and the Philadelphians LP. I think it was https://www.discogs.com/Rimsky-Korsakov ... ter/560867

I had an audio conversation with one of the engineers and asked whether he was trying to record the event as event or create a new configuration for LP. We usually recorded with either three spaced Omnis on a long pole or an AKG stereo mic hung about 25 feet above and out from the stage and I thought we got some great stereo, very realistic, slightly distant perspective as one would hear in balcony seats.

I never got any floor tickets at the Academy, but even before I worked at Magnetik productions, my brother worked in the concession stand and I could usually sneak in and find a second balcony seat for whatever I wanted to hear. BB King to Itzhak Perlman.

The EMI guy first had no idea what I was asking and then told me he was recording to create a compelling LP experience. I don't think any notion of Absolute Sound style 3-D realism ever entered his mind.

Anyway my advice to him was to put a mic on the railing of the second balcony. I sat in that region many times for many great players and got a mindblowing sparkling effect when a violin was tilted toward me up there. A violin is like a spotlight and it is so easy to miss this attention getting laser beam effect unless you are far and high...in the so-called cheap seats!

The Academy of Music was a legendary room with a lot of sonic character. The smaller theaters at the Kennedy center look like multiplex cinema rooms, no romance.

But all told, the behavior of sound in an auditorium is far different from the situation in a room where the lowest frequencies will not fit into the space and there is almost no distance from the transducers. in such circumstances, I think that the insights old Cool Hand provided are very apt, if natural tonal realism and perspective is the goal.

For those close enough to do it, check out the schedule of free concerts 365 days a year at the Kennedy Center. Couple good ones coming up this week. The podcasts are quite good sounding also.

http://www.kennedy-center.org/video/upcoming

I started going to hear Philly and Muti in 1986. My father was visiting from Australia and this was his first concert with an American orchestra which started off with a cracking Roman Carnival Overture. Our jaws dropped as they got faster than we thought possible but still with amazing accuracy.

Eventually we got front row seats on the top balcony and could look down on the chandelier. And no, you did not want to be in the back row since there were plenty of pillars in the way and the various overhangs did nothing to help the treble. But in the front row it was magic though it was vertigo time walking down the steep steps to our seats.

The hall was probably the most dry I have ever heard, but at least the sound was clean and clear.

Joe, perhaps you could enlighten me as to why the orchestra preferred to record elsewhere rather than in the Academy and why most reviewers thought the recordings were poor.

ray

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Walt

Any advantages of circular traktrix over rectangular?

I am not getting notifications reliably, so sorry for the delay.

Ray, the Academy was a super fast room but there were spots in the balcony that had quite an awesome vista. I heard dimensional effects there that I never heard anywhere else. Stravinsky in that top balcony center seat was one of the most amazing 3-D musical experiences I ever had.

If you stood center stage and scratched your fingernail on a piece of cardboard, it could be heard in the top balcony. The tight reverberation character of the room gave a sort of glow or aura. It was an especially cool effect on vocals.

I believe that the EMI guys were trying to add ambience to their recording with extra room mics because if you record simple stereo mic as we did, you got a dry Mercury Living Presence sort of flavor, which was probably not fashionable or desirable to those chaps.

The Academy was not real popular for recording because the Broad Street subway runs directly below the hall! You could see it on the meters if you had the mics on with the room empty.

We recorded the socialite matinee for WFLN-FM and some syndication. The Academy venue and the afternoon concert choice was of significance to the locals. We used three spaced omni or an AKG stereo mic hung in front of the stage and what we got really sounded like you were sitting in the Academy.

By the time I left Philly, around 1982, I had already become disenchanted with then-current multi mic mixed classical recordings and I was becoming a fan of older LPs already. I never even heard those EMI Muti recordings or at least I don't remember them. I was not impressed by the way they were going about things...seemed like a studio/soundstage approach.

My favorite shows in the Academy of Music were the twice annual B.B. King and Bobby Blue Bland gigs!! That was great stuff and really great sound. I was able to sneak in to anything through the late 70s-early 80s because my brother worked for the candy concession and I knew the security guards.

Walt, I have the best job in the world. Professional audio bum.

I did go to college...for 15 years... in anthropology and archaeology, so who is going to hire me? That is why I ended up in audio to begin with! Try getting a job with a Yale MA in Social and Cultural Anthropology...I was basically unemployable. Better not to have any degree, probably. I later went back to school and studied more useless and interesting stuff, but I am still basically unemployable.

Shashi, The only round tractrix i used was the Edgar "salad bowls." They were like lasers, with a 2x2" sweetspot. Hard, a bit brash. I didn't like them.

That Klangfilm horn is probably a bit beamy for auditorium use, which is why it was often used with louvered diffuser in front of the mouth. However, at listening distances of 10-25 feet, I didn't sense any dramatic HF beaming and the diffusers made the presentation less immediate. That tractrix is smooth as can be, rich and colorful, and super 3-D. One of the best I've heard.

Good horn, which is why it was a mainstay for 50 years.

I don't think abstract comparison of round vs rectangular are that useful. Some horns sound good and some others of similar specifications don't. Maybe the JMLC insights into termination come into play. I am not sure how well understood this used to be. Surely, it is a lot easier to measure time anomalies now.

There is not much in the historical horn literature and one could probably read it all in a week.

What the old pros at Siemens and Western Electric knew was never put down in print but they made some really nice horns.

Thanks for the info on the Academy. I miss climbing all the steps to the top floor (no elevator) to be greeted by Richard Woodhams warming up his oboe. He was always the first on stage and he still doing the same thing in Verizon Hall. I've never heard a recording of the orchestra that comes anywhere near to capturing his special 'sound'. Oddly enough, the following youtube of Richard talking about and demonstrating his reeds does sound like him playing, presumably because of proximity.

https://www.youtube.com/watch?v=iCtIabwlUoA&t=31s

ray

The SL450 rectangular horn is not suitable for me. For my application, I want the horn that start loading at about 500Hz, so I can cross over around 700Hz.

Looking at the 250Hz circular traktrixs. I ideally, I would get a 2" horn and a a 2"to1" adapter. so it can be used with both 2" and 1" CDs. Looks like they keep the mouth constant and truncate the throat to fit the CDs. 1" horn profile starts as a tangent at the throat, but the 2" throat starts at an angle. Is that a problem?

[url]
http://stereo-lab.de/produkt/sl250hz/[/url]

I posted a sweep of the original Klangfilm with 2" WE 594A driver.

download/file.php?id=904&mode=view

It goes lower than you need. Red trace is on axis at a couple feet.

We crossed it at 500hz third order, I think. Bass was a TA-4181 18" woofer in a dual tuned reflex box. One of the best speakers I ever heard and I think that the Klangfilm horn did a lot for that.

I also heard the Eurodyn system using this horn in numerous versions and that is a great great speaker.

It would be nice to find something easier to get and more local, but KL copy should be a good horn if the realization is up to snuff. I'll try to get user reports. Schick bought a pr. for one.

The only reservation I have is that the earlier KL horns were cast aluminum and this one is like the last KLs, resin. But the late model Eurodyns were quite good also, if not as sexy as the older ones.

GIP makes an aluminum copy based on my recommendation and that posted graph, which I showed to Mr. Suzuki to back up my raving. He probably sells them for more than my car is worth. Not really DIY friendly pricing at GIP! I might try to score a pair as a kickback.

Joe,

These SL450s are exact replicas of KL-302s?

Found another company from Korea which is making similar replicas of Eurodyn Klagfilm horns with 2" throat. They are stamped as KL280112.

http://www.ata21.com/gnuboard4/bbs/board.php?bo_table=p01&sca=Erodyn%20Horns%20for%20Klangfilm%20Project

You have to ask the German guy what he is doing exactly. I never saw the horn in the flesh.

The late model Eurodyns were not in a frame like in the picture. They came in a large baffle with 3x 10" woofers. i believe the horn had the exact same interior profile but I am not sure if it had a roll around the edge or it mounted dead flush like the early ones.

That Korean is making exact copies of the Klangfilm Eurodyn frame. Problem is that those horns have the screw on adapters for the Klangfilm drivers, which you will never find. But they do look like exact copies of the earlier Eurodyn horns. you would have to machine a bolt-on adapter for any American style driver.

The Klarton horn he makes is even more impossible to find parts to complete. That driver was a ribbon midrange compression driver! Very nice sounding. The woofer had a rod armature at the center that went down through the magnet. The whole thing may have been field coil...I can't remember but it was Pre-War. Can't buy those woofers at Radio Shack either.

I might actually know the Korean guy. There are so many "Mr. Lee" that it is hard to know who is who. Those prices look very nice... I'll investigate this one.